Orbi CBR40 downstream light blinking

My Orbi downstream light is flashing continually and I'm getting 15Mbps to 35Mbps, sometimes as low as 9Mbps. Sometimes my internet just drops out. My provider plan is up to 300Mbps, but I usually get 225 to 250Mbps+, which is fine. I've had the provider out to check what's wrong and, of course, their answer is that my equipment is bad. The Orbi and the RBS40 satellite I have are around 2.5 years old, so it seems unlikely to me that the equipment would have failed already. I have one computer hardwired to the Orbi CBR40; two iPads, two laptops, two iPhones, and an HP laser printer all connect wirelessly.

Everything I read online about a flashing downstream light tracks back to the provider and the line coming into the house. My provider claims they checked all of that and everything is in order on their end. I'm skeptical. My upstream is always at or over what I'm supposed to get, which is 30Mbps. So it doesn't make sense to me that my equipment is bad if my downstream is always way off but my upstream is always fine. Resetting the Orbi didn't help; sending a "refresh" signal to the Orbi by my provider didn't help; changing the coax from the main cable drop to the Orbi didn't help (there are no splitters on the line); resetting Orbi (factory reset) didn't help.

Looking for ideas to either rule out that my equipment is bad or that it could still be a provider issue. 

Thank you.